A burning smell coming from the refrigerator is never a good sign, but with some luck, maybe all you need to do is remove dust and dirt from the condenser coils. Otherwise, a burning smell could mean a burnt-up start relay and overload sensor, a failed compressor or fan problems.
Burnt Plastic and Metal Odor
When you notice a burnt plastic and metal smell coming from your refrigerator accompanied by some hazy smoke, the most likely culprit is the compressor's start relay. Start relay and overload sensors that burn out fail to kick on the compressor that circulates the coolant throughout the unit.
When this happens, temperatures inside the refrigerator continue to escalate. This combination part is meant to burn out to protect the compressor when issues occur. Most anyone with basic do-it-yourself repair skills can replace the start relay and overload sensor.
To access the start relay, remove the back panel of the refrigerator to expose the compressor after unplugging the unit from the wall. The start relay is attached to the compressor with an electrical plug leading from it. Examine the relay for burnt spots. If you find any, simply remove the relay and replace with a part that meets the manufacturer's specifications usually listed as original equipment manufacturer or OEM parts.
Burnt Dust or Dirt Smell
When dust, dirt or debris buildup on the condenser coils of the refrigerator, the compressor has to work harder to pump coolant through the system, which can cause it to overheat, blowing out the start relay and overload sensor or causing the compressor itself to fail. If you notice a faint burnt dirt or dust smell coming from the refrigerator, unplug it from the wall to clean the coils immediately.
To keep a compressor in a refrigerator from overheating, twice a year clean the condenser coils on the refrigerator. The coils may be at the back of the refrigerator or in front behind the kick panel, depending on the model you have. Vacuum them using the hose and brush attachment on your vacuum.
Burnt Chemical Smell
Because the compressor circulates the coolant through the refrigerator to cool or freeze the appropriate compartments, when it gives up the ghost, it can emit a burnt chemical smell. An indication of a compressor problem is the refrigerator's failure to cool and the lack of the compressor cycling on and off.
Compressors range in price from a few to several hundred dollars, depending on the model. For refrigerators under warranty, replacement by the manufacturer should not be a problem. But for a refrigerator already several years old, weigh the cost of the replacement and any labor against buying a new refrigerator to determine the option that has greater value.
A compressor replacement can add several years to the life of your refrigerator, since it is in the main component that keeps refrigerators cold. Replacing a compressor also requires flushing the refrigerator coils that may have been contaminated with acids when the compressor failed.
Electrical Burnt Odor
Refrigerators are also equipped with cooling coil fans and evaporator fans, but refrigerators that have coils on the back of the unit don't use a fan to cool the coils.
When the cooling fan fails to operate, the condenser coils fail to cool and the compressor itself can overheat. In newer refrigerators with electronics, a small circuit board controls fan operation. A burnt electrical smell could indicate a fan motor or circuit board failure. Unless you have experience using voltmeters and replacing circuit control boards, you will need to call a service technician for help.
The other fan in the refrigerator is the evaporator fan. You might smell an electrical burnt smell inside or outside of the refrigerator, and the items inside the fridge don't cool down, even though the compressor cycles on and off as it normally would. Another sign of an evaporator fan going bad is a distinct chirping sound that becomes louder once you open the refrigerator door.